The present invention relates to metallic ink based writing instruments and, more particularly, to metallic ink compositions for wick type writing instruments.
Currently, metallic ink writing instruments are enjoying great popularity. These are almost entirely in the form of a conventional style marker currently called a valve action marker (see FIG. 1). From the diagram, one can see that this is a complex device involving elaborate assembly. The valve action marker also involves shaking back and forth and then depressing, or pumping, the nib several times before ink will come down. As one can see, this is a rather cumbersome process.
Historically, metallic pigments have a large particle size greater than 20 microns; therefore, passage through a wick-style marker has not been possible. Instead, a valve-action marker is constructed with two steel balls in its ink chamber and a spring mechanism at the front in contact with the nib or tip. Since the specific gravity of the aluminum pigment is greater than water, it tends to settle rapidly. This is overcome by shaking back and forth, thereby re-mixing the aluminum particles in the ink. The pumping action on the paper forces the large particle aluminum pigments through the tip by applying pressure through the tip, thereby, producing ink and making writing possible.
Related conventional art includes U.S. Pat. Nos. 5,013,543 to Mercado; 5,219,560 to Kazuhiro; 5,106,881 to Hiroshi; 4,761,277 to Valdes; 4,872,905 to Bourne and 4,604,139 to Shoi, the contents of which are incorporated by reference herein. Regardless, the prior art has not delivered to date a wick-style marker which can deliver metallic pigments, i.e. inks, in writing instruments. As a result, metallic ink writing instruments have been more expensive, more complex to build and maintain, less reliable and have not fully realized their potential.